1. Technical Field
The present invention relates to a charge pump, and particularly to a charge pump for converting a voltage at an input node into a regulated voltage and outputting the regulated voltage.
2. Discussion of Related Art
A charge pump is a kind of power supply circuit for converting a voltage at an input node into a regulated voltage and outputting the regulated voltage to loads. Referring to FIG. 6, a common charge pump 50 includes: a capacitor 51, a first switch 52 coupled between a first electrode 510 of the capacitor 51 and an output node VOUT, a second switch 53 and an adjustable resistor 58 both of which are coupled in series between a second electrode 512 of the capacitor 51 and ground, a third switch 54 coupled between the second electrode 512 of the capacitor 51 and an input node VIN, a fourth switch 55 coupled between the first electrode 510 of the capacitor 51 and the input node VIN, a feed back loop 56 for monitoring a voltage at the output node VOUT, and an oscillator 57 for respectively controlling open/close states of the first switch 52, the second switch 53, the third switch 54 and the fourth switch 55.
By switching open/close states of the switches, the charge pump 50 is alternatively charged and discharged, thereby the output node VOUT outputs a voltage which is 2 times the voltage at the input node VIN.
However, noises will be induced on incoming current IIN during the switching of open/close states, which leads to fluctuation of the incoming current IIN and instability of the outputting voltage.
Therefore, what is needed is a charge pump having reduced noises on the incoming current IIN and stable outputting voltage.